import java.util.Scanner;

/**
 * Created with IntelliJ IDEA.
 * Description:
 * User: WHY
 * Date: 2022-11-29
 * Time: 16:52
 */
//字符集，如一个字符串为abcdwqeracb,最后输出为abcdwqer
public class Main {
    public static void main(String[] args) {
        Scanner scanner=new Scanner(System.in);
        String s=scanner.nextLine();
        //先定义一个空字符串
        StringBuilder stringBuilder=new StringBuilder("");
        for(int i=0;i<s.length();i++){
            int flag=1;//意味着不相等，后面用到这个条件就直接拼接
            for(int j=0;j<stringBuilder.length();j++){
                if(s.charAt(i)==stringBuilder.charAt(j))
                    flag=0;
            }
            if(flag==1){
                stringBuilder.append(s.charAt(i));
            }
        }
        System.out.println(stringBuilder);
    }
}
